Now, Barcelona joins a list of cities worldwide that have fallen victim to a growing trend.

"Steal a lorry or a car and then drive it into a crowd," former Swedish Prime Minister Carl Bildt tweeted after an April attack in Stockholm. "That seems to be the latest terrorist method."

Here's a look at some recent similar attacks and the motives behind them:

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Barcelona, Spain

An injured person is treated in Barcelona after a white van jumped the sidewalk in the historic Las Ramblas district.

Date of attack: August 17, 2017

Number of casualties: At least one person was killed and seven were hospitalized in serious condition, the Catalona government said shortly after the incident.

What happened: A witness told state-run TVE24 that he saw a van driving "around 80 kilometers" per hour. He said "there is no doubt it was intentional."

Why it happened: Barcelona police have confirmed the crash was a terror attack.

Charlottesville, Virginia

Pedestrians fly into the air as a car rams into demonstrators protesting against a white nationalist rally in Charlottesville on Saturday.

Date of attack: August 12, 2017

Number of casualties: A 32-year-old woman was killed and 19 people were injured.

What happened: A gray Dodge Challenger rammed into the back of a silver convertible on a narrow side street crowded with protesters in downtown Charlottesville. The Dodge driver slammed the car in reverse, going back up the street at a high rate of speed, dragging its front bumper.

The incident took place as rallies drew white nationalists and right-wing activists from across the country to the progressive college town.

London (London Bridge)

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Number of casualties: Eight people were killed and more than 40 were wounded.

What happened: Three men drove a van into pedestrians on London Bridge before going on a stabbing rampage at bars at nearby Borough Market. They were shot dead by police.

Inside the van, police found two blowtorches as well as what appeared to be 13 Molotov cocktails. The van also had office chairs and a suitcase. Police believe the attackers told relatives they were using it to move.

Butt is believed to have associated with the outlawed radical Islamist group al-Muhajiroun, co-founded by notorious hate preacher Anjem Choudary. Counter-terrorism sources told CNN he was was considered a potential threat to British security and was still under active investigation at the time he carried out the deadly assault.

In a raid of an east London apartment rented by Redouane, police found an English-language copy of the Koran opened at a page describing martyrdom and materials that may have been used to make the Molotov cocktails.

ISIS claimed responsibility for the attack, although the group provided no evidence for its involvement or details of the attack.

Stockholm, Sweden

What happened: A stolen beer truck barreled into pedestrians on a busy shopping street in the center of the Swedish capital before it plowed into a department store. Sweden stepped up its security. National counterterrorism, bomb and air assets also provided support.

Why it happened: The attacker, Rakhmat Akilov, had shown sympathies to extremist groups, including ISIS, Swedish police said. Akilov, 39, was from the central Asian republic of Uzbekistan. He admitted to carrying out a "terrorist crime," his lawyer said.

London (Westminster Bridge)

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Number of casualties: Five people died in the attack, including an American man and an unarmed police officer, and scores of others were injured.

What happened: Police say an assailant rammed his rental car into pedestrians on Westminster Bridge, not far from the UK Parliament. The suspect then entered Parliament grounds and fatally stabbed a police officer before being shot dead by other officers.

Why it happened: The attacker, identified as 52-year-old British man Khalid Masood, acted alone and was inspired by international terrorism, officials said.

"Clearly that's the main line of our investigation -- is what led him to be radicalized," said Mark Rowley, Britain's top counterterrorism officer. "Was it through influences in a community, influences from overseas or through online propaganda?"

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"The person who carried out the run-over in Nice, France, is one of the Islamic State soldiers and carried out the operation in response to calls to target nationals of the coalition which is fighting the Islamic State," the terror group said in a statement.

But French Interior Minister Bernard Cazeneuve said Bouhlel had no record of making militant statements and was not believed to be a member of ISIS.

"It seems he became radicalized very quickly," Cazeneuve said.

Berlin, Germany

Photos:Truck plows through Berlin Christmas market

Authorities examine a truck Tuesday, December 20, that crashed into a crowded Christmas market in Berlin the night before. At least 12 people were killed and 48 injured in what police are investigating as a likely terrorist attack.

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Photos:Truck plows through Berlin Christmas market

Emergency responders tow the truck's cab away from the crash site on December 20. Ariel Zurawski, owner of the truck company, said the truck may have been hijacked as it was transporting 25 tons of steel.

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Photos:Truck plows through Berlin Christmas market

An overview of the crash site on December 20 shows where the tractor-trailer drove over the sidewalk and into market stalls near the Kaiser Wilhelm Memorial Church.

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Photos:Truck plows through Berlin Christmas market

A rescue worker stands beside Christmas decorations that were scattered by the crash.

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Members of the press crowd around the crash site on December 20.

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A rescue worker looks at destroyed market stalls near the truck's trailer.

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Authorities investigate the crash site on December 20.

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Photos:Truck plows through Berlin Christmas market

Emergency responders treat an injured person on Monday, December 19.

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Photos:Truck plows through Berlin Christmas market

German police shine a flashlight onto the back of the truck.

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Photos:Truck plows through Berlin Christmas market

Emergency crews work near the crash site on December 19.

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Photos:Truck plows through Berlin Christmas market

Police officers stand next to the truck.

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Photos:Truck plows through Berlin Christmas market

Ambulances are seen where the incident happened in western Berlin.

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Photos:Truck plows through Berlin Christmas market

Police stand beside the damaged truck that crashed into the market.

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Photos:Truck plows through Berlin Christmas market

First responders load an injured person into an ambulance.

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A Christmas tree lies next to the truck.

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Police take someone into custody near the market.

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Police stand guard at the market after the crash.

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Photos:Truck plows through Berlin Christmas market

An armed police officer stands near the scene.

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Date of attack: December 19, 2016

Number of casualties: 12 people killed, at least 48 wounded

What happened: A tractor-trailer rammed into a crowd at a bustling Christmas market, which was filled with holiday shoppers. The suspect, Anis Amri, was killed later in a shootout with police in Italy.

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Why it happened: A video showed Amri pledging allegiance to ISIS, and the ISIS-affiliated Amaq news agency said the attack was carried out by "a soldier of the Islamic State" to target citizens of countries fighting ISIS.

But CNN terrorism analyst Paul Cruickshank said ISIS often uses that kind of terminology to refer to attacks by alleged sympathizers in the West.

"This should not be taken to mean the group is claiming it directed this attack," Cruickshank said.

The school's student newspaper, The Lantern, tweeted several photos on campus during the chaos, which was initially reported by university officials as an active shooter incident. It's possible the gunshots heard were those of police trying to stop the attacker, a federal law enforcement official said. "Students/bystanders have been moved back from the scene toward Arps Hall," The Lantern tweeted with this photo of a bicyclist.

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Photos:Ohio State students photograph lockdown

"There's at least one body bag present in front of Koffolt Labs," The Lantern tweeted during the lockdown. "OSU police still advising to take shelter. Situation not under control." The suspect in the Ohio State University attack rammed his car into a group of pedestrians before using a butcher knife to cut several people, OSU officials said. At least 11 people were hospitalized. The suspect was killed.

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Photos:Ohio State students photograph lockdown

"Police cars, fire truck and ambulance line 19th and College avenues near location where active shooter was reported," The Lantern tweeted.

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Photos:Ohio State students photograph lockdown

OSU senior Mackenzie Bart said she and four other female students barricaded themselves into a room in the Derby Hall building. "Staying safe and hope others are also," she tweeted.

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Photos:Ohio State students photograph lockdown

"Police are continuing to secure the area," The Lantern tweeted with this photo. "Follow @OSUPOLICE for updates."

Why it happened: Authorities said they believe Artan was inspired by terrorist propaganda from ISIS and the late Yemeni-American cleric Anwar al-Awlaki, two law enforcement sources said.

In a Facebook post shortly before the rampage, the Somali immigrant said he was "sick and tired" of seeing fellow Muslims "killed and tortured," federal law enforcement officials said.

He urged America "to stop interfering with other countries, especially the Muslim Ummah," a term for Muslim people at large. "By Allah, we will not let you sleep unless you give peace to the Muslims," he wrote.

Jerusalem

Photos:Deadly truck attack in Jerusalem

Israeli security forces gather around a flatbed truck at the site of a vehicle attack in Jerusalem on Sunday, January 8.

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Photos:Deadly truck attack in Jerusalem

A truck plowed into a group of soldiers in Jerusalem Sunday, killing four and injuring at least 13.

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Photos:Deadly truck attack in Jerusalem

The white truck at right was the one used in the attack.

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Israeli soldiers console each other at the site of the attack, which occurred on a popular promenade overlooking the walled Old City of Jerusalem.

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Israeli security forces and emergency personnel gather at the site of the vehicle attack. The attacker was shot and killed; note the bullet holes in the truck's windshield.

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A distraught Israeli soldier is consoled at the site of Sunday's attack.

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Photos:Deadly truck attack in Jerusalem

A group of soldiers had gotten off a bus and were getting organized with their bags when "the terrorist took the opportunity, ramming his truck into the group," Israel Police spokesman Micky Rosenfeld said.

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What happened: Authorities said 28-year-old Fadi Qunbar plowed into a group of Israeli soldiers on a popular promenade overlooking the walled Old City of Jerusalem.

Why it happened: The driver may have been an ISIS sympathizer, Israeli Prime Minister Benjamin Netanyahu said.

"All signs show he is a supporter of the Islamic State," Netanyahu said in January. "We know there is a sequence of terror attacks, and it's quite possible that there is a connection between them, from France, Berlin and now Jerusalem."

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Why it happened: Authorities said they believe Couture had been "radicalized." He was arrested in July 2013, the Royal Canadian Mounted Police said.

"When he was arrested, he was about to go to Turkey," police spokeswoman Martine Fontaine said. "We stopped him as he was about to leave Canada for terrorist actions. He was questioned when he was arrested."

Terror expert: Radical cleric continues to inspire

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It said a four-wheel-drive pickup is needed -- "the stronger the better."

"To achieve maximum carnage, you need to pick up as much speed as you can while still retaining good control of your vehicle in order to maximize your inertia and be able to strike as many people as possible in your first run," the article says.

John Miller, deputy commissioner of intelligence for New York police, has said ISIS calls on supporters to use cars as weapons if they have no other means of attack.

"The ISIS call, as well as that of other terrorist groups, has been to use what you have on hand," Miller said in 2015.

"And that means if you can make a bomb, you're a bomber. But if you can't, use a gun. And if you can't find a gun, use a knife. And if you can't find a knife, use a car. So when we look at that, that is a broad spectrum of threats, and it's something to prepare for."